This invention relates generally to hand tools. More particularly, the present invention relates to an improved composite pry bar and striking tool having a construction which significantly increases the strength of the tool without a significant corresponding increase in weight.
In manufacturing a tool such as a pry bar or striking tool, a variety of competing design considerations are at stake. On the one hand, it is desirable to have a tool that is as light as possible, to provide for easy use by consumers. On the other hand, the tool must have the structural integrity to withstand the variety of stresses that will be placed on it. Solid steel pry bar and striking tools have been widely used in the past, but provide an often unacceptable increase in weight to achieve the desired structural integrity and impacting strength. The use of a wooden tool body would unacceptably compromise structural integrity to lessen the weight.
An alternative is the use of rods formed from resin coated fibers. The basic technique for running filaments through a resin bath and then through an elongated heated die tube to produce a cured composite rod of the same shape as the die tube has been known for some time. See, for example, U.S. Pat. Nos. 2,948,649 and 3,556,888. This method, however, produces a solid extruded product which may be unacceptably heavy and/or too rigid for many applications.
The weight problem can be alleviated by an existing process to extrude hollow tubes utilizing a die tube with the center filled, leaving an annular cross-section through which the resin coated fibers are pulled. This weight reduction is achieved, however, at the cost of significantly reduced bending or flexural strength in comparison with a solid rod, resulting in a tool body which would not be suitable for use in certain high stress applications such as pry bars and striking tools. Further, to increase interlaminar strength of the tube forming fibers, a substantial percentage of fibers running other than in a longitudinal direction have been thought to be required.
Accordingly, there has been an ongoing need for improved composite tool bodies to provide significantly increased tensile and flexural strength without a corresponding increase in the weight of the handle. The present invention fulfills these needs and provides other related advantages.